The present embodiments relate to hydraulic pump systems.
In one example application, a manual hydraulic pump can be used to stow an aircraft component. One such aircraft component can include a ram air turbine (“RAT”). During normal flight conditions the RAT remains stowed inside the aircraft (e.g., fuselage or wing), but upon complete loss of power to the aircraft the RAT is deployed and generates power for the aircraft using an airstream produced by the speed of the aircraft. The RAT can also be deployed during installation and door rigging, where it is not uncommon for the RAT to be deployed (and thus stowed) over ten times.
Stowing the RAT after a deployment can differ depending on the aircraft. Generally in larger aircraft, RAT systems have an actuator connected to the aircraft's hydraulic systems which allows the RAT to be stowed using the aircraft's operating pressure. However, in small and mid-sized aircraft, such as regional and business jets, RAT systems are generally not connected to the aircraft's hydraulic systems. In such instances where the RAT is not connected to the aircraft's hydraulic systems, a manual hydraulic pump is used to stow the RAT in a ground operation. The manual hydraulic pump has a small displacement and requires extensive manual stroking to stow the RAT. In fact, stowing the RAT generally requires over 100 strokes for a dual stage pump, and over 150 strokes for a single stage pump. Consequently, use of a manual hydraulic pump to stow a RAT creates a physical burden and increases installation time due to the continual deployment and stowing of the RAT during installation.